EA Demuxer: make rev2 flag optional

Originally committed as revision 14474 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/electronicarts.c

@@ -178,6 +178,7 @@ static int process_audio_header_elements(AVFormatContext *s)
         }
         switch (revision2) {
         case  8: ea->audio_codec = CODEC_ID_PCM_S16LE_PLANAR; break;
+        case -1: break;
         default:
             av_log(s, AV_LOG_ERROR, "unsupported stream type; revision2=%i\n", revision2);
             return 0;